Computational Steering

Computational steering is the online management of the execution of an application and its resources for the purpose of either performance improvement or application exploration. Generally, visualizations are used to provide the user with insight into the state and behavior of the underlying system, and as a feedback mechanism, enabling users to gauge the effectiveness of these parameter adjustments. Tools and techniques for interactive steering are being applied to simulation applications and environments, for network configuration and management, load balancing and scheduling, modeling and design, the interactive refinement of scientific visualizations, and performance optimization of WWW servers and parallel I/O systems. Researchers are working to develop both applicationspecific steering solutions and general tools to facilitate the steering process. Often, work on application-specific tools carries over into the development of more general tools. For example, the SCIRun scientific programming environment described by Parker was originally designed to solve specific problems in computational medicine, but has been extended to serve as a more general problemsolving environment for computational science and engineering problems, supporting the interactive construction, debugging, and steering of large-scale scientific computations. Similarly, the VIPER system discussed by Oberhuber was originally developed for online visualization and interactive steering of parallel computational fluid dynamics programs. Oberhuber describes how VIPER has been integrated with codex, a tool developed to test and control communication by use of control patterns, to form an environment for tuning, steering, and testing. Researchers working to develop efficient, reliable tools for the computational steering of distributed systems encounter many “juicy” research questions such as efficient I/O handling, time coherency of data, efficient checkpointing strategies, evaluation of global predicates, and consistent application of steering updates. The